1. Field of the Invention
The present invention relates to an ultrasonic endoscope, which uses ultrasonic waves for the diagnosis of a diseased tissue. Especially, the present invention relates to the construction of the distal end of the ultrasonic endoscope.
2. Description of the Related Art
In the ultrasonic endoscope, an ultrasonic probe having ultrasonic wave vibrators is provided at the distal end of the endoscope. The ultrasonic probe sends ultrasonic waves and receives echoes of the sent ultrasonic waves.
For the scanning method, a radial scanning or a linear scanning is used. For example, when diagnosing an organ (body-cavity), into which the ultrasonic endoscope cannot be inserted, the radial scanning is performed. The endoscope is inserted toward an organ adjacent to the observed organ, ultrasonic waves are sent radially from the ultrasonic probe. Conventionally, a mechanical-type radial scanning is applied, where a series of ultrasonic wave vibrators is aligned along an axis of the probe and revolves on the axis to send the ultrasonic waves radially.
However, in the case of the mechanical type radial scanning, a color-image, partially colored by Red (R), G (Green), B(Blue), which is effective for diagnosis of the diseased areas, cannot be displayed on the monitor.
Further, in an ultrasonic endoscope, the solid or hard ultrasonic probe is provided at the distal end of the endoscope. Therefore, when moving the endoscope towards the observed portion, it is important not to cause pain with the attachment at the distal end portion. To facilitate this, a far greater response performance of the bending portion to the operator""s manipulation is required compared to a normal endoscope.
Therefore, an object of the present invention is to provide an ultrasonic endoscope that is capable of obtaining an observed-image effective for diagnosis without degrading the response performance of the bending portion.
An ultrasonic endoscope according to the present invention is an endoscope for performing electronic radial scanning. A bending portion formed in a tube is connected to the point of a flexible tube, which is inserted in a body, or organ. The flexible tube is normally connected to a manipulator portion of the endoscope, and an operator, such as doctor, bends the bending portion by manipulating a manipulating knob, which is operatively connected to the bending portion. Namely, the bending portion bends by remote control.
The bending portion bends along two predetermined directions. Normally, the bending portion bends along an up-down direction and a left-right direction, which are perpendicular to each other. The up-down direction and the left-right direction are defined on the basis of the holding-posture of the manipulator portion, the connection between the manipulator portion and the flexible tube, and so on. The manipulating knob for bending the bending portion toward the up, down, left, or right direction, is provided at the manipulator portion, and the operator manipulates the manipulating knob as required. For example, the manipulating knob is composed of an up-down knob for bending the bending portion along the up-down direction and a left-right knob for bending the bending portion along the left-right direction.
The ultrasonic endoscope is a fiber-scope type endoscope or a video-scope type endoscope. In the case of the video-scope type endoscope, the ultrasonic endoscope is connected to a video-processor having a light source and signal circuits and is connected to an exclusive ultrasonic wave diagnosis apparatus. An image sensor is provided at the distal end of the endoscope, and further, an image signal cable connected to the image sensor, a fiber-optic bundle for the light source, a delivery tube for providing liquid or air, and a forceps tube for inserting a forceps, are arranged in the endoscope. On the other hand, in the case of the fiber-scope type endoscope, the ultrasonic endoscope is connected to a light source unit and is then connected to the ultrasonic wave diagnosis apparatus. Further, an image fiber-optic bundle for optically transmitting the object image is provided in the endoscope, in place of the image signal cable. Note that, the fiber-optic bundle for the light source and the delivery tube may be composed of a pair of fiber-optic bundles and a pair of delivery tubes, respectively.
An ultrasonic probe for the electronic radial scanning is operatively connected to the bending portion. For example, a solid point-base portion is connected to the bending portion and the ultrasonic endoscope is attached to the point-base portion.
The ultrasonic probe has a plurality of ultrasonic wave vibrators, which are arranged circumferentially to perform the electronic radial scanning. The plurality of ultrasonic wave vibrators send ultrasonic waves radially around a center axis of the ultrasonic probe and receive echoes of the ultrasonic waves.
According to the present invention, a flexible circuit board is provided in the endoscope. The flexible circuit board transmits signals associated with ultrasonic waves and echoes, so that an ultrasonic-image, representing a section-image in the body, is obtained at the ultrasonic wave diagnosis apparatus. As electronic scanning (not mechanical scanning) is performed, an ultrasonic color-image is obtained as required by simultaneously sending multiple ultrasonic waves, each frequency of which is different, or an ultrasonic pulse-width image is obtained by coloring in accordance with contrast of the echoes. These images cannot be obtained by mechanical radial scanning.
In the bending portion, the flexible circuit board is constructed of a plurality of flexible circuit board strips so as to allow a bending motion, namely, to be capable of withstanding the bending motion. The plurality of flexible circuit board strips extends along a central axis of the bending portion. Since the signal-transmitting member in the bending portion is composed of a plurality of flexible circuit board strips, snapping does not occur while the bending portion is manipulated. The plurality of flexible circuit board strips enables the circumferential arrangement of the ultrasonic wave vibrators, namely, the electronic radial scanning. Note that, the width of each flexible circuit board strips is defined in accordance with a radius of the bending portion.
Further, according to the present invention, the plurality of flexible circuit board strips are arranged in the bending portion such that an excellent response performance for the bending manipulation is realized. Note that, the response performance represents whether the bending portion bends along the determined direction precisely without inclining in an undetermined direction. While inserting the flexible tube into the organ, the operator, as required, bends the bending portion along only one of two directions, or one of the up-down direction and the left-right direction, to pass the flexible tube through the organ smoothly. Almost all operators bend the bending portion along the up-down direction. Speaking concretely, most operators insert the flexible tube by bending the bending portion toward the up-direction and returning it toward the neutral position, as required.
In the endoscope of the present invention, the plurality of flexible circuit board strips are arranged in the bending portion such that a bending-resistance to the bending motion occurs symmetrically with respect to a primary central line. The primary central line is defined on a section of the bending portion, crosses the central axis of the bending portion, and corresponds to one of the two bending-directions (normally, the up-down direction). The plurality of flexible circuit board strips are arranged in accordance with the arrangement of the various members extending through the bending portion, such as the fiber-optic bundle, the delivery tube, and the forceps tube.
As the bending-resistance (flexural-resistance) occurs symmetrically, in other words, the flexural rigidity along the direction to be bent has symmetry with respect to the primary central line, the response performance to the bending manipulation is excellent and the bending portion bends toward the desired direction precisely. Therefore, when inserting the flexible tube, the operator can manipulate the bending portion so as not to cause a pain to the patient.
To produce a bending-resistance having precise symmetry, preferably, each members provided in the endoscope, such as the fiber-optic bundle, the delivery tubes, and so on, is arranged so as to have symmetry with respect to the primary central line on the section. For example, in the case of the video-scope type endoscope, the fiber-optic bundle, the delivery tube, the forceps tube, and the image signal cable are arranged so as to have symmetry with respect to the primary central line. Then, the plurality of flexible circuit board strips are arranged so as to have symmetry with respect to the primary central line in the section. Therefore, a bending portion with high response performance to the bending motion is easily arranged, or manufactured.
To arrange the plurality of circuit board strips without difficulty, preferably, the width and thickness of each of the plurality of circuit board strips on the section is substantially the same.
To securely and easily arrange the plurality of circuit board strips symmetrically, and to maintain the symmetrical arrangement during the bending motion, a plurality of bundles, each of which is composed of at least two flexible circuit board strips, may be formed. For example, if the number of circuit board strips is even, each bundle can be composed of two flexible circuit board strips. The plurality of flexible circuit board strips bends in each bundle, namely, the flexure direction is the same in each bundle. Therefore, the bending-resistance to the bending motion is stable and occurs symmetrically.
When the section form of the circuit board strips flexes, the bending-resistance to the bending motion tends to occur unsymmetrically. To produce a bending-resistance having precise symmetry, preferably, the plurality of circuit board strips are arranged along the central axis such that the section-form of each of the plurality of circuit board strips becomes substantially straight. In this case, each flexible circuit board strip bends smoothly, and the bending-resistance is stable and occurs symmetrically.
To maintain the symmetrical arrangement during the bending motion of the bending portion, the plurality of circuit board strips may not be positioned on a line of action, namely, the primary central line. Namely, preferably, the plurality of circuit board strips are arranged such that the plurality of circuit board strips are not on the primary central line in the section.
As for the total construction of the flexible circuit board, the flexible circuit board may be composed of the flexible circuit board strips (pieces), which are connected to the ultrasonic wave vibrator separately. However, in order to easily arrange the flexible circuit board so that it is symmetrical in the bending portion, preferably, the flexible circuit board is formed by partially cutting a single rectangular flexible circuit board such that a plurality of flexible circuit board strips are formed. Then, the cut rectangular flexible circuit board is rounded so as to form a cylinder. The strip portions are then gathered together at the end furthest from the board and a cone-like structure is formed. The plurality of circuit board strips may be arranged such that they are not on the primary central line in the section.
To symmetrically and easily arrange, preferably, the number of flexible circuit board strips is eight, and the width of each strip is substantially the same. Further, preferably, the eight circuit board strips are bundled such that two adjacent circuit board strips form one bundle.